The number of prescriptions written for antidepressants in wealthy countries has doubled in the past 20 years.

This increase is mostly due to people staying on antidepressants for a long time.

Many people who have had depression continue to take antidepressants for years for fear that if they stop, they might have a relapse.

Most studies of antidepressants and relapse have been done in people taking the medication for less than eight months.

We wanted to know whether antidepressant treatment was still effective when people have been taking the pills for several years.

Our study, published in the New England Journal of Medicine, found that remaining on antidepressants long-term reduced the risk of a relapse, but many people were able to come off them safely.

All the patients had a history of at least two episodes of depression, had been taking their antidepressants for a minimum of nine months, and felt well enough to consider stopping the pills.

All patients, from 150 GP surgeries in England, were interviewed by a researcher, and we excluded those who had symptoms of depression that met the criteria for a clinical diagnosis. We recruited people who were taking the most commonly prescribed antidepressants – sertraline, citalopram and fluoxetine.

These are all selective serotonin reuptake inhibitors (SSRIs) that increase serotonin levels in the brain. We also included mirtazapine, a newer antidepressant that has been increasing in use in the UK.

We randomly allocated people to one of two groups: half of the study participants stopped taking their antidepressant medication and half continued.

The group who stopped their medication were given reduced doses of their antidepressants for up to two months until they were on placebo only.

The other group continued with the same dose of the antidepressant they were already receiving.

Neither researchers nor patients knew which group people were allocated to. This type of “double-blind study” helps to reduce bias.

After the study started, we collected data from participants at intervals of six, 12, 26, 39 and 52 weeks after they started the trial.

So, remaining on antidepressants is appropriate for many people receiving long-term treatment from their GP. We didn’t find any evidence that the antidepressants in our study had serious side-effects.

Remaining on antidepressants did not guarantee wellbeing in our study - 39 percent of people who continued with their regular dose had a relapse within a year.

The decision to remain on long-term treatment is offset by any potential side-effects and many people prefer not to take medication for many years.

In our study, many people were able to come off their antidepressants safely without a relapse. In the group who stopped their antidepressants, 44 percent did not relapse after a full year.

Even among those who did relapse after stopping, only half chose to return to an antidepressant prescribed by their GP.

Many patients might decide to stop their antidepressants, in consultation with their doctor, knowing there might be a risk of relapse.

If people who want to discontinue their antidepressants are regularly monitored by their GP, it may be possible to prevent relapses with different treatments, such as talk therapy. For example, studies have shown that mindfulness based cognitive therapy is effective at preventing relapse.

In our study, people who stopped their antidepressants after reducing the dose over two months were more likely to experience withdrawal symptoms, such as irritability and difficulty in concentrating, than those who continued treatment.

Yet, by the end of the study, a year later, 59 percent of the discontinuation group were not taking antidepressants.

Our study only provides information about the average probability of relapse. We do not yet know why some people are able to come off their antidepressants and some cannot. Further research may help us to predict who can stop antidepressants safely.

Our study provides an estimate of the risk of relapse if someone carries on with long-term antidepressants or decides to stop them.

These findings will help doctors and patients to make an informed decision together on whether or not to stop long-term antidepressant treatment.

(Gemma Lewis and Glyn Lewis are Researchers at University College London)

(This is an opinion piece and the views expressed above are the author’s own. The Quint neither endorses nor is responsible for them. This article was originally published on The Conversation. Read the original article here.)